1. Field of the Invention
The present invention relates to a recovery apparatus that scoops up, with buckets, the oil contained in water-soluble liquid coolant such as cutting fluid or grinding fluid for use in machine tools. More particularly, the invention relates to the structure of the buckets.
2. Description of the Related Art
In the process of cutting metal work pieces, water-soluble liquid coolant consisting mainly of much water is used for the purpose lengthening the lifetime of tools, enhance the process precision of the work pieces and promote the disposal of chips.
The coolant discharged from the machine tool contains oil such as the operating oil and lubricating oil used in the machine tools. As known in the art, the oil may decay or degrade the coolant. If the coolant is to be used over again, the oil should be immediately removed from the coolant.
Hitherto, to remove the oil from the coolant, a reserve tank is provided on the passage through which the coolant circulates, and temporarily stores the dirty coolant containing the oil. The reserve tank incorporates an endless belt that is made of cloth or metal mesh.
In the reserve tank, the oil contained in the coolant drifts at the surface level of the coolant. This is because the oil has smaller specific gravity than water that is the main component of the coolant. The belt runs between a position where it is immersed in the coolant and a position where it protrudes above the surface level of the coolant. Thus, the belt passes through the surface level of the coolant. As the belt so runs, it catches the oil floating at the surface level of the coolant. The oil is thereby removed from the coolant.
With the conventional structure, the belt that catches the oil penetrates only the surface level of the coolant. It can hardly contact the oil at a sufficiently large area. Consequently, the oil floating at the surface level of the coolant can hardly stick to the belt. This renders it difficult to recover the oil at high efficiency.
The longer the belt is repeatedly used, the more it will be clogged. The belt must therefore be cleaned or replaced by a new one at regular intervals. Much time and labor is required to clean or replace the belt.
Recently, a recovery apparatus has been proposed, which is free of this problem. This apparatus comprises a chain conveyor and a plurality of buckets. The chain conveyor is provided in a reserve tank and extends above the surface level of the coolant in the tank. The buckets are attached to the chain conveyor and recover the oil floating at the surface level of the coolant.
The buckets scoop up the oil together with some coolant, as they move up from the surface level of the coolant. Nonetheless, they are shaped to scoop up oil only. Hence, much of the oil scooped up will overflow the rim of each bucket as the bucket is moved upwards.
As a result, only little oil remains in each bucket. Further improvements should be made to increase the efficiency of recovering the oil.